In the programming world, this means NOT. It is mostly used in boolean expressions, mostly found in if statements, to express the non-equality of something.

It can be used with an '=' sign like this: 3 != 4, meaning 3 does not equal 4. This is a true expression, and so the expression would return TRUE. However, if I put: ((6-3) != (5-2)) I'm basically saying 6-3 is not equal to 5-2, or 3 does not equal 3. But 3 DOES equal 3. So this expression would return false.